1. Technical Field
The present disclosure relates to a wireless communication technology, and more particularly, to methods for beamforming in a wireless communication system and apparatuses for the same.
2. Related Art
A multi-antenna technology may mean a signal processing technology using a plurality of antennas in at least one of a transmitter and a receiver. The multi-antenna technology may be used for not only provision of better services (e.g., higher data rate per user) but also provision of enhanced system capacity (e.g., more users per cell) and enhanced system coverage.
The multi-antenna technology may include a diversity, a beamforming, a spatial multiplexing (i.e., multiple input multiple output (MIMO)), etc. In the case of diversity, multiple antennas in at least one of the transmitter and the receiver may further provide diversity effects in addition to fading on radio channels. For this, the multiple antennas should have low mutual correlations with each other.
In the case of beamforming, multiple antennas in at least one of the transmitter and the receiver may generate a beam to maximize antenna gain for a specific direction or suppress interference signals between beams. For this, each of the multiple antennas may operate based on high mutual fading correlations or low mutual fading correlations. In the case of spatial multiplexing, both of the transmitter and the receiver may generate a plurality of communication channels on a wireless interface. For this, higher data rate can be provided in a restricted bandwidth without a significant reduction of coverage.
Meanwhile, the beamforming may be classified into a co-located beamforming (CBF), a distributed beamforming (DBF), etc. In the CBF, a single base station performs beamforming by using a plurality of antennas. In the DBF, a plurality of base stations perform beamforming by using at least one antenna, respectively.
According to wireless communication environments, CBF may have a better performance as compared to DBF, or DBF may have a better performance as compared to CBF. Therefore, it is required to perform CBF or DBF selectively according to wireless communication environments.